In a statement, Richard Lessner, executive director of the American Conservative Union, called the platform "a bland and uninspiring document" that lacked "solid conservative meat." Although most conservatives enthusiastically support the lengthy platform section on fighting terrorism, Mr. Lessner said, its "open-ended commitment" to keeping troops in Iraq and Afghanistan is troubling.

His harshest criticism fell on President Bush's plan for the new temporary worker program.

"This unfortunate initiative allows those who enter America illegally to become legal residents and apply for citizenship," he said. "This idea was D.O.A. among conservatives when the president first broached it, and it is still offensive."

In a private e-mail message that circulated among conservatives at the platform hearings and on Capitol Hill, Paul S. Teller, legislative director of the conservative House Republican Study Committee, forwarded Mr. Lessner's statement, adding:

"It confirms, as was made so clear to me during the time of President Reagan's funeral and laying in state, that President Bush has no broad vision--and certainly no conservative vision-- for the United States of America. All he has is a random assortment of policy prescriptions, many of which contradict one another. And let's not forget his primary goal on federal spending, to cut the deficit in half in five years. Wowwee."

Last night, Mr. Teller declined to comment on the message, except to say it was a private communication to trusted friends. The potential effects of conservative discontent on the election remain to be seen. No conservative third-party candidate has gathered much momentum, and few conservatives are likely to pull a lever for Senator John Kerry on Election Day.

Bush campaign spokesmen often say the party is more united than ever, with support for the president comparable to their backing in Mr. Reagan's first term. Still, many Republican strategists argue that in a tight race motivation and turnout among the base voters could be decisive.